html,body{height: 100%;}
body{margin: 0;padding: 0;}
.box{
    width: 200px;
    height: 100px;
    padding: 20px;
    line-height: 100px;
    text-align: center;
    float: left;
    margin-left: 20px;
    font-size: 28px;
    border-radius: 20px;
    color: #fff;
    cursor: pointer;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.5);
}
.add-friend,.friend-info,.friend-list{
    width: 400px;
    height: 100%;
    position: fixed;
    right: 0;
    top: 0;
    background-color: #f1f1f1;
    /*左侧加阴影*/
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.5);
    /*点击从右侧划出*/
    transform: translateX(0);
    transition: transform 0.5s;
    display: none;
}
.login-box{
    width: 100%;
    height: 100%;
    position: fixed;
    z-index: 99999999;
    top: 0;
    left: 0;
    background-color: #ffffff;
    display: block;
}
.user-login{
    /*上下左右居中，来点阴影好看一点*/
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 400px;
    height: 400px;
    border-radius: 20px;
    background-color: #fff;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.5);
}
.user-info{
    width: 50%;
    height: 100px;
    padding: 20px;
    margin: 20px auto;
    line-height: 100px;
    text-align: center;
    font-size: 28px;
    border-radius: 20px;
    color: #fff;
    background-color: darksalmon;
    cursor: pointer;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.5);
    position: relative;
}
.login-out{
    position: absolute;
    right: 20px;
    top: 15%;
}